Various functions, including safety, holdability, and ease of egress and ingress (ease of getting in and out) are required for vehicular seats, such as automobile seats. In addition, there are also many demands for the enhancement of passengers' comfortability, such as seat comfort and vibration absorption. Vehicular seats are one of large parts among the interior parts of automobiles and there are various demands also with respect to the appearance and design thereof.
To meet diversified needs in automobile seat design, a wide variety of uneven shapes, curved surfaces, or curved lines must be formed on seat surfaces. It is a critical challenge to develop a seat structure and a manufacturing method for implementing such a structure.
An example of the background arts in this technical field is the technology described in Patent Literature 1. Patent Literature 1 discloses a cushion body of a seat for automobiles. The cushion body is formed of a plurality of unit cushions obtained by covering a pad material with a trim and a supporting body supporting each unit cushion. A predetermined number of locking members provided in either or both of the pad material and the trim are locked on the supporting body and each unit cushion is thereby attached to the supporting body.
The patent literature states that according to the above-mentioned cushion body of a seat for automobiles, it is possible to contribute to reduction of a work load and variation in product quality and to enhance the degree of freedom in designing.
Patent Literature 2 discloses a drawing structure for seat skins. The drawing structure is provided on the inner face side of a seat skin with a drawing cord having a hook positioned at an opening in a cushion pad and hooked and secured on the axis line of an insert wire exposed from the opening. A predetermined drawing line is provided in the surface of the seat skin by the drawing cord including the hook and the seat skin is assembled to the cushion pad with the shapes thereof matched with each other.
The patent publication states that according to the above-mentioned drawing structure for seat skins, it is possible to draw in the surface of a seat skin without fail, assemble the seat skin to a cushion pad with the shapes thereof accurately matched with each other, and prevent twitched wrinkles, a dimple-like depression, or the like from being formed on the decorative surface side of the seat skin.
Patent Literature 3 discloses a trim drawing structure for seats. The trim drawing structure includes a resin hook provided with: a base portion made of a soft material attached to a pair of trims covering the surface of a seat pad; and a hook portion provided at the tip of the base portion and locked on a locked member provided on the seat pad side. The paired trims are drawn in and locked on the locked member by the resin hook and are thereby secured on the seat pad.
The patent publication states that according to the above-mentioned trim drawing structure for seats, it is possible to easily attach and remove the resin hook to and from the trims and dismantle the seat and to firmly secure the trim to the seat pad without fail.
Patent Literature 4 discloses a drawing structure for skin materials configured to lock a part of a skin material covering a vehicular seat on the pad member side such that the part is drawn in to form a design slit in the vehicular seat. A rail member having openings is laid on the pad member in a position corresponding to the position of formation of the design slit and a flexible plate body that can be bent and deformed in the direction of thickness is attached to the back of the skin material opposite to the rail member. A plurality of engaging protrusions that can be engaged with the above-mentioned openings are formed at intervals on the entire surface of the plate body opposed to the rail member. The engaging protrusions are engaged with the openings in the rail member such that the engaging protrusions can be relatively moved along the rail member.
The patent publication states that according to the above-mentioned drawing structure for skin materials, it is possible to stably lock the skin material in correspondence with the outside shape of the pad member such that the skin material is drawn in.
Patent Literature 5 discloses a vehicular seat that is provided with a value adding member enhancing designability, functionality, and the like and in which a drawing wire for drawing in a skin covering the outer surface is buried in a pad as a cushion material. A recess for fitting the above-mentioned value adding member is formed in the pad and the value adding member is provided on the back thereof with a hook. The drawing wire is buried toward the inner part of the recess along the recess and the skin covers the entire outer surface of the pad including the recess. The value adding member is fit into the recess from outside the skin and the skin is locked on the drawing wire through the hook.
The patent publication states that according to the above-mentioned vehicular seat, it is possible to draw in the skin and fit the value adding member with efficiency and ease through a simple configuration and to enhance the disignability of the seat.